Changes to ghc

Changes to ghc:
commit 12369d6065547215337fdec9587e5fdecd57a45e
Author: Patrick Palka <patrick@parcs.ath.cx>
Date:   Fri Nov 8 09:41:24 2013 -0500

    SysTools.getTempDir: don't retry after catching a does-not-exist error

    Previously, a command like

    $ ghc -tmpdir blah Foo

    where the directory blah/ does not exist, would loop forever: getTempDir
    would repeatedly try to create a temporary subdirectory inside blah/,
    catching the does-not-exist error thrown by createDirectory and
    retrying, in vain, with another suffix.

    Now instead the above compiler invocation will fail with an error:

    blah/ghc25781_0: createDirectory: does not exist (No such file or directory)